Avascular necrosis (AVN) of the femoral head
- The most common cause ~ of is Legg-Calvé-Perthes disease, an idiopathic
disease that occurs primarily in boys between ages 4 and 8 years.
- non-idiopathic etiologies may include trauma, infection, prolonged steroid
treatment, sickle cell disease, mucopolysaccharidoses, and epiphyseal
- Pain is usually mild, and a limp may be present for several months before
medical attention is sought ("painless limp") - (vs painful limp:
- Ipsilateral gluteal weakness (Trendelenburg)
- Loss of medial (internal) rotation and abduction are the
primary physical findings.
- Early x-rays may be negative, but then get widening of medial joint
space or a smaller femoral head; flattening of femoral head, then
reossification and healing.
- . MRI or bone scan can be helpful early if
x-rays are normal. Epiphyseal dysplasia may also be seen on XR (note that
bilateral symmetrical involvement is very rare in LCP disease).
- Stages of LCP that can be seen on XR are
- Usually self-limited
- Treatment includes rest, NSAIDS, bracing, and possible surgery
CHLA Board Review 2005